1. Brief Description of the Related Art
Various prior art door-closing systems have been disclosed that self-close patio sliding doors with bottom tracks. Typically, these prior art devices utilize cylindrical tubes having a weight that is connected to a cable, the cable passes over a pulley, and the pulley is anchored in the doorjamb. Each of these door-closing systems utilizes a valve means at the bottom of the tube to control the flow of air passing therethrough.
Typical prior art sliding door closers are disclosed in U.S. Pat. No. 3,334,444 to Hargrove (hereinafter, “the '444 Patent”), and U.S. Pat. No. 4,884,369 to Tatham (hereinafter, “the '369 Patent”). As with typical prior art devices, the '444 Patent and the '369 Patent teach that when a door is opened, a weight rises in the tube; when the door is released, the weight drops in the tube according to the port adjustment in the tube, and the door closes. (See the '444 Patent, Column 5, Lines 54-61; and the '369 Patent, Abstract).
Another prior art device, U.S. Pat. No. 4,649,598 to Kinsey, et al. (hereinafter, “the '598 Patent”), utilizes a weight and pulley system such as that described above with respect to the '369 Patent, together with a pneumatic seal located at the top of the weight and designed to buffer the speed at which the door closes. (See the '598 Patent, Column 3, Lines 47-56).
However, none of the prior art devices provide an automatic door-closure mechanism for a set of sliding doors that permit the sliding doors to fully break out into an open position whereby the first sliding door is placed into an open position by sliding over, and proximate to, a second door, and the set of both doors is opened with respect to a door frame.
As an example, there remains a need within hospitals that utilize trackless breakout sliding doors in Intensive Care Units (ICU). These doors allow ICU rooms to maintain a negative pressure which is required because the hospitals are utilizing these rooms as isolation units for persons with a contagious disease. One way to have these rooms pressurized is to have the doors closed all of the time. In recent years, the demand for the automatic self-closing device has become more prevalent.
In other situations such as clean rooms, there also is a need for this self-closing device to inhibit the entry of dust and other particles into the clean room. It is has been found that clean rooms also can be negative pressure rooms. Alternatively, automatic self-closing doors might be desirable to keep particles or odors inside a room such as in laboratories where there is chemical testing, mixing, and any odors that are unwanted in other areas of the facility.
An automatic self-closing device also provides an appropriate fire door protection where typical trackless sliding doors may be used. When the smoke detectors and alarms go off, a magnet will disengage and the door closure device will automatically close the door panel to cut down on drafts from one area.
With hotels, homes, and office buildings, there is a need for a more efficient closing device for the sliding door. An improved automatic closing device for sliding doors will improve energy efficiency, convenience, security, and safety. Any improvement in self-closing doors known in the prior art will therefore be an improvement in these areas as well.
Based on the shortcomings of the prior art described above and other known prior art, the object of this present invention is to provide an automatic closing device for both the trackless breakout sliding door and the patio sliding door. Another object of the present invention is to provide additional unique features for an automatic closing device including a novel pulley housing, alternative cable fabrication material, alternative means for attaching the cable to the trackless breakout sliding door, alternative pulley housing fabrication material and alternative weighted piston fabrication material.
2. Description of the Invention
The present invention comprises an automatic door-closing device used on trackless breakout sliding doors typically installed in hospitals for ICU doors, clean room facilities, fire doors, and laboratories. This automatic door-closing device also can be used on patio sliding doors for energy efficiency, convenience, security, and safety of having a patio sliding door automatically closed.